Effect of Nyctanthes arbor-tristis on cardiovascular parameters and metabolic syndrome in fructose-induced hypertensive rats

Abstract

We investigated the effects of methanolic extract of Nyctanthes arbor-tristis (MNAT) 100, 200 and 400 mg/kg/day post-operative for 6 weeks on ECG, basal mean arterial blood pressure (MABP), heart rate, respiratory rate, vascular reactivity, antioxidant activities of enzyme superoxide dismutase (SOD) and catalase (CAT), levels of thiobarbituric acid reactive substances (TBARS), serum levels of leptin, adiponectin, glucose, triglycerides, cholesterol, uric acid, insulin, sodium and potassium in fructose-fed rats. A high-fructose-diet (fructose 10%, w/v) ad libitum for 6 weeks was used to induce hypertension in male Wistar rats (150–200 g). Sixty albino Wistar rats were randomly divided into a group of six, each group containing 10 animals. Group I was considered as normal control which received chow pellets and normal drinking water ad libitum for 6 weeks. Group II received fructose (10%) solution instead of normal drinking water for 6 weeks. Group III received fructose (10%) solution instead of drinking water ad libitum and MNAT at a dose of 100 mg/kg post-operative for 6 weeks. Group IV received fructose (10%) solution instead of drinking water ad libitum and MNAT at a dose of 200 mg/kg post-operative for 6 weeks. Group V received fructose (10%) solution instead of drinking water ad libitum and MNAT at a dose of 400 mg/kg post-operative for 6 weeks. Group VI received fructose (10%) solution instead of drinking water ad libitum and enalapril at a dose of 10 mg/kg post-operative for 6 weeks. Physiological parameters, ECG, heart rate, respiratory rate and blood pressure vascular reactivity to various drugs were measured and recorded by the invasive method. The antioxidant activities of enzyme SOD and CAT, levels of TBARS, along with serum levels of leptin, adiponectin, glucose, triglycerides, cholesterol, uric acid, insulin, sodium and potassium were measured. Cumulative concentration-response curve (CCRC) of Ang II and acetylcholine (Ach) was recorded. MNAT treatment decreased MABP and altered vascular reactivity to various catecholamines. The activities of SOD and CAT enzymes exhibited a considerable increase and the levels of TBARS in the liver were reduced by MNAT treatment. MNAT has shown decrease in the plasma level of triglycerides, cholesterol, insulin and sodium while increase in plasma adiponectin and potassium levels. The CCRC of Ang II was shifted towards the right by MNAT treatment using an isolated strip of rat ascending colon. MNAT treatment increased the contractile characteristics of the rat ascending colon in the CCRC of ACh as compared to the fructose-treated group. MNAT treatment reduced fructose-induced tissue damage due to the consequence of metabolic syndrome (MetS). MNAT is rich in flavonoids and, therefore, has powerful antioxidant properties. The findings show that by battling oxidative stress caused by fructose (10%) and reducing Ang II activity, MNAT may be able to prevent the development of high blood pressure caused by fructose. MNAT has antihypertensive action and reverses MetS in the fructose-induced hypertensive rat model.